The present invention relates to a new and improved heart assist device, and more specifically is directed to a device in which one expandable member is placed directly within the left ventricle of the heart and another expandable member is placed directly in the right ventricle of the heart or in the aorta to facilitate complete ejection of blood during systole.
In certain pathological conditions, the heart, and principally the left ventricle, cannot contract fully during systole, so there is incomplete emptying of the heart. The amount of blood remaining in the ventricle at the end of systole is the "dead volume" or "dead space" and represents unused pumping capacity.
Damage to the left ventricular muscle arises from a variety of causes, whether chemical, physical, bacterial and viral, and leads to a decrease of contractility and therefore to a decrease of ejection fraction. Consequently, congestive heart failure results, which may be correctable to varying degrees by pharmacological or mechanical intervention.
In intractable left ventricle failure, when it is not possible to increase the stroke volume, the "dead volume or space" at the end of the systole is increased.
The prior art devices appear generally to be in the nature of U.S. Pat. No. 3,266,487, which discloses devices that are placed within the aorta. None of the devices are placed directly within the left ventricle where they can operate more efficiently. U.S. Pat. No. 3,592,183 concerns a ventricular assist device having an aortic balloon with a somewhat similar shape to that of the present invention, but it does not perform the same functions, and it is not positioned within the left ventricle. U.S. Pat. No. 4,261,339 pertains to a device having an aortic balloon.